Disclosed herein is a vehicle seat, and particularly, a vehicle seat capable of stably absorbing impact energy generated upon a rear end collision.
Generally, upon a so-called rear end collision in which another vehicle collides with a rear part of a vehicle such as an automobile or the vehicle collides with another vehicle in a rearward running mode, an occupant sitting on a vehicle seat abruptly moves rearward and an upper body of the occupant is inclined rearward due to the inertia force.
In general, a seatback of the vehicle seat is formed in a manner such that a cushion material is placed on a metallic seat back frame and is coated by a skin material. However, as described above, since the occupant abruptly moves rearward upon a rear end collision or the like, there is a case in which the deformation amount of the seatback with respect to the movement is not sufficient and a load applied to the human body of the occupant may not be efficiently reduced. Further, since a large load is applied to the seatback, there is a concern that a problem may occur in the seatback.
In order to solve such problems, Japanese Patent No. 4200580 (“the '580 patent”) discloses a technique of reducing a load applied to an occupant in a rearward movement state by employing a configuration in which a side frame is bent when a rearward load is applied to an upper portion of a seat back frame.
In the seat back frame disclosed in the '580 patent, when a rearward load is applied to the seat back frame with the rearward movement of the occupant upon a rear end collision or the like, the side frame is bent so that the rearward impact energy is absorbed by the seat back frame. However, since the seat back frame of the '580 patent may not deform the side frame by confining the deformation position (the bent position) thereof, the side frame is bent at any point in the up to down direction. As a result, since the bent point may not be confined, the impact energy is transmitted to the entire seat back frame so that the impact energy absorption efficiency is degraded. Accordingly, it is difficult to stably reduce the impact energy.
Therefore, the present applicant has proposed a technique of absorbing the impact energy by deforming the seat back frame (Japanese Patent Application No. 2010-273867). Specifically, a flexible bent portion is formed in a lower frame, and when an impact load generated upon a rear end collision or the like is applied to the seat back frame, the bent portion is first bent to efficiently absorb the impact energy. In this way, the impact energy may be efficiently absorbed by confining the deformation position of the seat back frame.
However, in the above-described related art, there has been demanded a technique capable of stably absorbing the impact energy by further confining the bent portion. That is, there has been demanded a vehicle seat that is stably bent by causing a specific position to be easily deformed with respect to a complex input load applied to a seat back frame upon a rear end collision.
Further, there has been demanded a technique capable of more efficiently absorbing the impact energy in a manner such that the rigidity of the portion other than the specific position (deformation portion) which is easily bent is improved to easily regulate the position of the deformation portion and the specific position is deformed without deforming the portion other the specific position even when a complex input load is applied thereto.
Further, in the above-described related art, when the seat back frame is deformed to be inclined rearward, the rearward inclined angle increases too much, depending on the magnitude of the applied impact energy, and hence there is a concern that an occupant sitting posture may change and hence a sitting feeling may be degraded. Accordingly, there has been demanded a technique capable of controlling the seat deformation amount (the rearward inclined angle) by regulating the warpage amount in the vehicle seat of which the seat back frame is warped and inclined rearward when the impact load is applied thereto.
Further, in the seat back frame that confines the deformation position, a configuration is supposed in which two or more deformation positions are provided to highly efficiently absorb the impact energy. That is, as the configuration of the seat back frame that is warped when the impact load is applied thereto, a configuration is supposed which includes a deformation portion that is deformed when the impact load is applied thereto and other deformation portions that are deformed when the deformation of the deformation portion is transmitted thereto. In such a configuration, from the viewpoint of efficiently absorbing the impact energy, there is a need to appropriately transmit the deformation of the seat back frame generated by using the deformation portion as a starting point from the deformation portion to other deformation portion(s). That is, in the vehicle seat equipped with the seat back frame including plural deformation portions, there has been demanded a technique capable of smoothly absorbing the impact energy by appropriately transmitting the deformation generated upon a rear end collision or the like from one deformation portion to the other deformation portion.